1. Field of the Invention
The invention relates to a correlated set of iron type golf clubs. More particularly, the invention relates to a set of iron type golf clubs correlated with linearly spaced lofts and lengths in conjunction with improved design efficiency.
2. Description of the Prior Art
Golf club design has evolved from relatively unforgiving forged blade irons to cast cavity back irons, and then into oversized and even some hollow designs. All of these developments have been made in an effort to improve playability for the average golfer.
Along with these changes, however, golf club manufacturers have decreased club face lofts and increased club lengths. As those familiar with the golf industry will certainly appreciate, these changes have been made in effort to provide golfers with increased distance.
While golfers have gained added length from these longer irons, the manufacture of irons capable of providing longer carries has increased the difficulty of squarely hitting these irons. The increased difficulty brought about by the increases in club lengths has countered the design improvements aimed at enhancing the playability of golf clubs. These difficulties are most pronounced in the longer irons (especially the 3 irons and 4 irons, but including the 5 irons, 6 irons and 7 irons), which are now more difficult to hit despite the addition of various head design enhancements.
The increased lengths of golf clubs, and iron type golf clubs in particular, have also resulted in lighter club heads. Besides the increased length and decreased loft, the center of gravity found in most iron type club heads has generally remained relatively close to the face and the moment of inertia (which provides a direct correlation to the clubs resistance to twisting and therefore off-center-hit performance) has not significantly increased.
Additionally, lofts have not been strengthened uniformly throughout the set; the short iron lofts have been made four to five degrees stronger while the lofts of long irons have been strengthened only one to three degrees, on average. This has resulted in inconsistent and unequal ball carry distances for the average golfer.
In view of the many changes surrounding the recent development of iron type golf clubs, a need exists for a system by which golfers may take advantage of these many improvements while minimizing the inherent shortcomings of these new designs. The present invention provides such a system by offering a correlated set of iron type golf clubs.
It is, therefore, an object of the present invention to provide a correlated set of iron type golf clubs designed so as to improve performance. The set of clubs includes a plurality of iron type golf clubs having linearly spaced lofts such that a first iron type golf club has a loft which is x degrees greater than the loft of a second iron type golf club and the second iron type golf club has a loft which is x degrees greater than a third iron type golf club and subsequent iron type golf clubs increase in loft at the same rate. The plurality of iron type golf clubs also have lengths which are linearly spaced such that a first iron type golf club has a length which is y inches less than the length of the second iron type golf club and the second iron type golf club has a length which is y inches less than the length of the third iron type golf club and subsequent iron type golf clubs decrease in length at the same rate. The set of iron type golf clubs is further designed such that the design efficiency increases as the loft of the golf clubs decreases, wherein design efficiency is defined as:
DE (design efficiency)=((MOIx*MOIy)*(Club Head Volume))/Club Head Mass 
where,
MOIx=moment of inertia around the x-axis
MOIy=moment of inertia around the y-axis.
It is also an object of the present invention to provide a correlated set of iron type golf clubs wherein the loft of the golf clubs is linearly spaced at approximately 4 degrees.
It is a further object of the present invention to provide a correlated set of iron type golf clubs wherein the lengths of the golf clubs are linearly spaced at approximately 0.75 inches.
It is another object of the present invention to provide a correlated set of iron type golf clubs wherein the set of iron type golf clubs includes long irons, middle irons and short irons.
It is also another object of the present invention to provide a correlated set of iron type golf clubs wherein the long irons are of an iron-wood construction.
It is still another object of the present invention to provide a correlated set of iron type golf clubs wherein the middle irons are of a hollow back construction.
It is yet another object of the present invention to provide a correlated set of iron type golf clubs wherein the short irons are of a cavity back construction.
It is also an object of the present invention to provide a correlated set of iron type golf clubs wherein the set of irons includes a 3 iron, 4 iron, 5 iron, 6 iron, 7 iron, 8 iron, 9 iron and pitching wedge, and the 3 iron and 4 iron are of an iron-wood construction, the 5 iron, 6 iron and 7 iron are of a hollow back construction and the 8 iron, 9 iron and pitching wedge are of a cavity back construction.
It is a further object of the present invention to provide a correlated set of iron type golf clubs designed so as to improve performance. The set of clubs includes at least three iron type golf clubs, wherein the first iron type golf club has a volume of approximately 85 cc to approximately 140 cc, the second iron type golf club has a volume of approximately 45 cc to approximately 85 cc, and the third iron type club having a volume of approximately 10 cc to approximately 45 cc.
It is also an object of the present invention to provide a correlated set of iron type golf clubs wherein the set of irons includes a 3 iron, 4 iron, 5 iron, 6 iron, 7 iron, 8 iron, 9 iron and pitching wedge, and the 3 iron and 4 iron are of an iron-wood construction having a volume of approximately 85 cc to approximately 140 cc, the 5 iron, 6 iron and 7 iron are of a half hollow construction having a volume of approximately 45 cc to 85 cc and the 8 iron, 9 iron and pitching wedge are of a cavity back construction having a volume of approximately 10 cc to 45 cc.
It is another object of the present invention to provide a correlated set of iron type golf clubs wherein the 3 iron and the 4 iron have a loft range between approximately 15xc2x0 and approximately 30xc2x0, a length range between approximately 37.5 inches and approximately 42 inches and a head mass between approximately 150 grams and approximately 260 grams; the 5 iron, 6 iron and 7 iron have a loft range between approximately 25xc2x0 and approximately 40xc2x0, a length range between approximately 36 inches and approximately 39 inches and a head mass between approximately 200 grams and approximately 300 grams; and the 8 iron, 9 iron and pitching wedge have a loft range between approximately 35xc2x0 and approximately 50xc2x0, a length range between approximately 33 inches and approximately 37.5 inches and a head mass between approximately 150 grams and approximately 260 grams.
Other objects and advantages of the present invention will become apparent from the following detailed description when viewed in conjunction with the accompanying drawings, which set forth certain embodiments of the invention